Flaps Rigging (5)

5 hours

It's time to finally get the control surfaces set up!  I started with the flaps.

The flaps attach to the flap drive tube with a short pushrod on each flap.  The first challenge I ran into was that as soon as I tried to connect the pushrods it was obvious that they were too long.  I think the plans specified a 3" piece of threaded rod, plus the rod end bearings on each end.  After a bunch of trial and error I figured out a good length was actually more like 1-7/8".  Anyway that took a while but once I got that figured out I was able to connect the pushrods and start working on adjusting them.

The process of adjusting the pushrods was pretty much just setting the flaps in the neutral position with the actuator all the way up.  That's pretty much it I guess, and then the downward travel is just whatever you get from the actuator's travel.  Anyhow, while setting the top of the travel I found that the flaps would just barely contact the back of the wing right at the top of their range, which would then cause the fuse to pop before the actuator stopped.  I upped the flaps fuse from 5 amps to 7.5 amps, and then I ended up just setting them as far up as I could without popping it.  With some measuring I found that position to be about 0.3 degrees down from where the plans specified.  I think that's probably close enough and as good as I can get it, plus with the flaps up I can easily lift them a little farther just with the slop in the actuator, so if that isn't aerodynamically neutral the air will probably just push them there anyway.

I also realized that with the pushrods installed you can't access it at all to adjust the length!  The only way to really get at it, and especially to tighten the jam nut, was to let the flap hang straight down and then pivot the pushrod parallel to the flap so it also dangled below the fuselage.  In order to get the pushrod into that position, I had to file a little notch in the bottom of the flap skin to let the pushrod go by.

Then it was reasonably possible to tighten the jam nuts.

Finally, after a many iterations of adjustments, tests, and popped fuses, I got the flaps to match each other, go pretty much all the way up, and they appear to travel about 27 degrees down from neutral.  I've read on the forums that around 27 degrees is pretty common so I think it'll work.

Control Pushrods, Part 2 (1.5)

1.5 hours

Continuing with the pushrods.  The flap and short aileron pushrods just had to be assembled from hardware; the long aileron pushrods had to be built from tube stock.

I cut the tubing to length and drilled/riveted the machined fittings to each end.

Then I just screwed in the rod end bearings.  The drawing calls for an initial overall length, which I set, and then I tightened the lock nuts.

All three pairs done!

 

Flaps Part 4 (1)

1 hour

Both flaps are now done!

Flaps Part 3 (4.5)

4.5 hours

Lots more progress on the flaps!  The right flap is done and the left flap is not far behind!

Flaps Part 2 (3)

3 hours

More progress on the flaps.  The RH one just needs all the parts deburred, and on the LH one I need to fit one more rib plus the hinge and then deburr everything.

Flaps (0.5)

0.5 hours

Not much time to work today, but I did get the flap skins cut out!

Flap Revision

Alright so I did hear back from Sonex about that one dimension I was unsure about on the flap skins within a couple days, I just forgot to post the results.  They updated the flap drive rib locating dimension, but they also removed a cutout from the flap skins, since that cutout took material away from where the drive rib would actually be located!

Sonex published a revised aerobatic flap drawing to cover all the updates.  Unfortunately I already made that cutout so I'll have to redo the skins!  Sonex stands by their product as usual though, so they are sending me two new skins plus the ribs I had already drilled to my skins.

Anyway here's the difference I'm talking about.

The original drawing

Revision A

Flaps Part 2 (3)

3 hours

I got the left flap skin cut out, and the center and outboard ribs drilled to the skin.  I'll have to wait on the drive ribs for both flaps until I hear back from Sonex.  Then I went back and updrilled and deburred the ribs for both flaps.

Flaps (2.5)

2.5 hours

Today I got the RH flap skin cut out.  It took me a little while to figure out the compound angles that the plans called for!

I cut the skin with snips.  I've seen people do it with a band saw or miter saw, but I didn't feel like setting up any power tools.  The flap skins come in 72" pieces, but I'm doing the Sport Acro setup so the longest part of the flaps are only 54.5".  I started by cutting the piece down to 56" long to make it more manageable.  It's a pain to cut through the middle of a sheet with snips, but once you get close to your line it gets real easy to cut accurately.

A full 72" piece of skin material.

Precision is the name of the game!!!  This was my extremely rough cut to within a couple inches of the final length.

Cutting the final size.

Sheet metal is sharp; be careful not to add too much extra character to your workbench!

Once I had the RH skin cut, I started laying out the ribs.  These shortened flaps only get three ribs each, including the drive ribs.  I laid out the holes and drilled the outboard and center ribs, but I noticed the dimension locating the inboard (drive) rib didn't look right.  The dimension didn't quite line up with where the rib was actually depicted in the drawing.  I called Sonex about it, and Kerry said it's probably not correct, but they'll have to get back to me with the correct dimension.  I called it a day at that point!

This 50-23/32" dimension is supposed to locate the drive rib, but it doesn't actually line up with where the rib is.  Chances are that means it isn't right!

Flap & Aileron Parts, Part 2 (6)

6 hours

More control surface parts!  I asked Sonex about those CCC-34 rivets that are called out to attach the nutplate to each flap drive rib.  Turns out it was a typo, and it was supposed to be SSC-34's which I do have!  They came with the hydraulic brakes kit.  I also noticed that I was supposed to countersink all the holes on the flap drive ribs and use flush rivets.  So good thing I hadn't gone ahead and riveted it yet.

I picked up this microstop countersink, and it's great.  It took a few minutes so set up, but once it was set I was able to knock out all the countersinks pretty fast, and they are consistent!

I also found that if I drilled the through hole for the nutplate up to 3/16" on the rib, I could use a cleco to hold the nutplate in place so I could transfer the two mounting holes.  After that, I updrilled the hole to 17/64", which as far as I know is the proper clearance hole size for a 1/4" bolt.

Anyway, now these two parts are finally done!

Aileron drive ribs also done!

These two channels were tricky to rivet because the holes are so close to the flange.

Not a big deal, I just ground some more material off of my low profile rivet puller!

This poor thing is probably going to break any time now as I keep shrinking it, but for now it works great!

Next was the aileron counterweight assemblies.  The kit comes with a 1" thick block of lead, which just needs to be cut in half to produce the two weight blocks.  I cut it on the bandsaw, which was actually really easy.

With those two things ready, I just had to build the assemblies to go with them.  I used some tabletop geometry to locate the first rib on it's corresponding plate.

Once that was set I transferred a few holes from the plate to the rib, and then clamped that rib to its opposing rib and transferred the holes to it.  That took care of locating all the parts on the first assembly.

Then I took each rib off and transferred the holes again to the other opposing rib, to create two identical pairs.

With everything now located, I just had to transfer the rest of the holes, updrill, deburr, and rivet!

The next step was drilling the lead blocks in between the plates.  This was not as easy!  I found that once the drill bit started cutting it would get sucked in real quick and then either get stuck or just break.  After snapping a couple of #40 bits I started the rest of the holes on #30, which worked a little better.  I probably could have started even larger.  Anyway I eventually got all the holes up to 3/16".  Then I took them apart to deburr and scrape off the chunks of lead that were wedged between the plates.

I had to hammer the crap out of these bolts to get them through the lead!

Done!

 I think between these six little parts I pulled almost 200 rivets, so if they say this kit is around 10,000 rivets that's like 2% right there!

Flap & Aileron Parts (3)

3 hours

I'm starting on the flaps and ailerons now, beginning with the drive ribs for each surface.

Flap drive rib parts

Flap drive ribs coming together

The flap drive ribs each get a nutplate which calls for two CCC-34 rivets, which I do not have on hand.  I'll have to get my hands on some before I can finish these parts!

Flap drive ribs ready to rivet once I get the nutplates installed.

Aileron drive ribs in progress

Flap and aileron drive ribs, plus two little channels that will be part of the aileron counterweights ready to rivet.